There are various methods used to prepare single metallocene and dual metallocene catalyst systems containing an activator-support. These catalyst systems can be used to polymerize olefins to produce olefin-based polymers, such as ethylene/α-olefin copolymers. For the same initial components of the catalyst system, it would be beneficial for these catalyst systems to have higher catalyst activity and to produce polymers having high molecular weights, as a result of the method used to prepare the catalyst system. Accordingly, it is to these ends that the present disclosure is directed.